The Web Server Gateway Interface (WSGI) is a standard interface
between web server software and web applications written in Python.
Having a standard interface makes it easy to use an application
that supports WSGI with a number of different web servers.

Only authors of web servers and programming frameworks need to know
every detail and corner case of the WSGI design. You don't need to
understand every detail of WSGI just to install a WSGI application or
to write a web application using an existing framework.

wsgiref is a reference implementation of the WSGI specification
that can be used to add WSGI support to a web server or framework. It
provides utilities for manipulating WSGI environment variables and
response headers, base classes for implementing WSGI servers, a demo
HTTP server that serves WSGI applications, and a validation tool that
checks WSGI servers and applications for conformance to the
WSGI specification (PEP 333).

See http://www.wsgi.org for more information about WSGI,
and links to tutorials and other resources.